Method of abating of effluents from chemical vapor deposition processes using organometallic source reagents

ABSTRACT

A method and apparatus for abatement of effluent from a CVD process using a source reagent having a metal organic loosely bound to a organic or organomettalic molecule such that upon exposure to heat such bond is readily cleavable, e.g., copper deposition process involving the formation of films on a substrate by metalorganic chemical vapor deposition (CVD) utilizing a precursor composition for such film formation. The abatement process in specific embodiments facilitates high efficiency abatement of effluents from copper deposition processes utilizing Cu(hfac)TMVS as a copper source reagent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for abatement ofeffluent from any CVD process using a source reagent having a metalorganic loosely bound to an organic or organometallic molecule such thatupon exposure to heat such bond is readily cleavable e.g., abatement ofeffluents from processes involving the deposition of copper on asubstrate by chemical vapor deposition (CVD).

2. Description of the Related Art

Copper deposition has become one of the most important and rapidlygrowing areas in integrated circuit manufacturing. Deposition of coppercan be accomplished by various techniques, with chemical vapordeposition (CVD) becoming progressively more widespread.

The precursors used in copper CVD, however, are relatively new andlimited information has been published on their abatement. One of themajor chemistries currently being employed for CuCVD utilizesCu(hfac)TMVS as a copper source reagent. This precursor, Cu(hfac)TMVS,wherein hfac=1,1,1,5,5,5-hexafluoroacetylacetonato and TMVS is trimethylvinyl silane, CH₂═CH—Si(CH₃)₃, is commercially available from SchumacherDivision of Air Products and Chemicals, Inc. (Allentown, Pa.) under thetrademark CupraSelect.

In the CupraSelect™ process, the generally accepted mechanism for thedeposition of copper from the Cu(hfac)TMVS precursor by CVD involves theliberation of TMVS on the wafer surface and its intact desorption. Thisis followed by collision and disproportionation of two Cu(I)(hfac)molecules, to yield Cu(0) (metal) and Cu(II)(hfac)₂. Copper metalthereby is incorporated in the growing film, while Cu(II)(hfac)2 desorbstherefrom.

Under certain process conditions, Hhfac (CF₃—CO—CH═COH—CF₃), theprotonated, acidic form of hfac, is produced in the film formationprocess. This can occur as a result of the addition or presence ofwater. Alternatively, Hhfac can form in consequence of the use of H₂ asa reducing gas in the CVD process.

Thus, in the use of Cu(hfac)TMVS as a copper source reagent for CVD, thereaction by-products of the copper deposition process include Hhfac,TMVS and Cu(II)(hfac)₂. These reaction by-products are correspondinglypresent in the effluent from the copper CVD process when Cu(hfac)TMVS isemployed as a copper source reagent, and require abatement in thetreatment of the effluent gas from the process.

One of the major process challenges in the CupraSelect™ process relatesto the fact that the Cu(hfac)TMVS precursor tends to decompose in thehot environment of the dry vacuum pumps that are used in the process.This decomposition produces corresponding decomposition products thatseverely shorten vacuum pump life.

Schumacher has developed a technique for the abatement of waste gasspecies from the CupraSelect™ process. In this abatement techniquecopper CVD species escaping the CVD process chamber are passed through aheated section of the vacuum line downstream from the CVD chamber, andupstream of the vacuum pump, so that the copper species are convertedinto volatile materials (Cu(hfac)₂ and TMVS, with deposition of copperon the heated section internal surfaces). These volatile materialssubsequently pass through the dry vacuum pumps without deposition andwithout attendant pump damage from deposited solids. The valuable hfacmaterial is recovered downstream from the dry vacuum pump in a coldtrap, which condenses the Cu(hfac)₂ while allowing the TMVS to passthrough. The valuable Cu(hfac)₂ can then be collected and recycled to anupstream Cu(hfac)TMVS manufacturing operation.

The Schumacher technique is described in detail in “Safety andenvironmental concerns of CVD copper precursors,” B. Zorich and M.Majors, Solid State Technology; September 1998, pp. 101-106.

Despite its utility, the Schumacher efficient abatement techniquesuffers from a number of deficiencies.

One major deficiency relates to the fact that there is a significantamount of Cu(hfac)TMVS and Cu(hfac)₂ passing through the process system,which can result in excessive copper emissions in the discharge ventgas.

Another deficiency of the Schumacher technique relates to the fact thatsignificant amounts of free TMVS pass through the process system. TMVSis highly flammable, having a flashpoint of −19° C., and a lowerexplosive limit (LEL) of 0.5% in air.

A further deficiency of the Schumacher technique relates to the factthat the cold trap is not very efficient for removing Cu(hfac)₂. Thecold trap also presents significant operational difficulties, since thecold trap must be removed and separately processed in order to recoverCu(hfac)₂.

The semiconductor manufacturing industry, and other industrialoperations that utilize CupraSelect™ reagents for formation of copper onsubstrates, would therefore be greatly benefited by a process thatovercomes the aforementioned disadvantages.

The foregoing issues are not unique to the CupraSelect™ process or othercopper metallization processes using other Cu CVD precursors, such asCu(hfac)-R where R is any of a series of organic or organometallicmolecules. Some examples include Cu(hfacac)-3-hexyne,(C₅HF₆O₂)Cu—(C₆H₁₀), and Cu CVD precursors containing organo moietiessuch as 3-hexyne (CH₃—CH₂—C≡C—CH₂—CH₃), dimethylcyclooctadecene (DMCOD)and 3-methylhex-ene-yne (3MHY). These issues also apply to other CVDprocesses which use a source reagent having a metal organic looselybound to a organic or organometallic molecule such that upon exposure toheat such bond is readily cleavable.

SUMMARY OF THE INVENTION

The present invention relates to a method and apparatus for abatement ofeffluent from any CVD process using a precursor (source reagent) havinga metal organic loosely bound to a organic or organometallic moleculesuch that upon exposure to heat such bond is readily cleavable. Moreparticularly, the present invention relates to a method and apparatusfor abatement of effluent from a process for depositing copper on asubstrate from an organocopper source reagent.

In one aspect, the invention relates to a method wherein the effluentfrom the CVD process is contacted with a sorbent having sorptiveaffinity for the organometallic source reagent, as well as for byproductspecies deriving from the deposition process utilizing such sourcereagent.

The sorbent may comprise a physical sorbent and/or a chemisorbent, asdesired to effect desired abatement of effluent species.

A pump may be disposed upstream of the sorbent, and arranged to maintainpredetermined pressure conditions in the upstream deposition process,with (1) a pre-pump heating device operative to at least partiallyconvert organocopper species in the effluent to conversion products thatare less susceptible to deposition in the pump, and/or (2) a post-pumpcold trap operative to remove condensable and/or solidifiable componentsfrom the effluent.

The above-described method may further comprise monitoring the effluentdischarged from the sorbent contacting step, to detect breakthrough of aselected component, e.g., by a quartz microbalance detector.

The invention in another aspect relates to an apparatus for abatement ofeffluent from a CVD process using an organometallic source reagent, suchapparatus comprising:

a sorbent bed having sorptive affinity for the source reagent andbyproduct species deriving from the source reagent; and

a flow path joining the process in gas flow communication with thesorbent bed so that effluent is flowed through the sorbent bed, to atleast partially remove source reagent and deposition byproduct speciesfrom the effluent.

A pump may be disposed upstream of the sorbent, and arranged to maintainpredetermined pressure conditions in the upstream deposition process,with (1) a pre-pump heating device operative to at least partiallyconvert organocopper species in the effluent to conversion products thatare less susceptible to deposition in the pump, and/or (2) a post-pumpcold trap operative to remove condensable and/or solidifiable componentsfrom the effluent.

The apparatus may further comprise an endpoint sensor operativelyarranged to sense breakthrough of one or more effluent components ineffluent from the sorbent bed.

The apparatus may further include a semiconductor manufacturing facilityin which copper is deposited on a substrate, e.g., by a CVD process.

Other aspects and features of the invention will be more fully apparentfrom the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a thin film fabrication facilityincluding an effluent abatement system according to one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS THEREOF

The present invention provides an effluent abatement system fortreatment of effluent streams from any CVD process using a sourcereagent or precursor having a metal organic loosely bound to a organicor organometallic molecule such that upon exposure to heat such bond isreadily cleavable. More particularly, the present invention relates to amethod and apparatus for abatement of effluent from copper depositionprocesses.

In a specific embodiment described hereinafter, effluent from aCupraSelect™ CVD process is subjected to treatment.

Although illustratively described herein with reference to a specificembodiment involving treatment of effluent from a CupraSelect™ process,it will be recognized that the apparatus and methodology disclosedherein may be widely and effectively employed for the abatement ofstreams deriving from operations involving any CVD process using asource reagent or precursor having a metal organic loosely bound to aorganic or organometallic molecule such that upon exposure to heat suchbond is readily cleavable including a wide variety of other coppersource reagents.

The abatement apparatus and methodology of the invention may beefficiently utilized with the optional end point detection capabilityhereafter described, to determine the approach to exhaustion of thesorbents that are used in abating organic and organometallic species ineffluent streams containing same. Such determination in turn may beemployed for change-out of the sorbent medium approaching exhaustion, oralternatively, such determination may be employed to effect switch-overfrom an exhausted sorbent medium, e.g., in a scrubbing unit containingsame, to a fresh scrubbing unit, for uninterrupted operation of theprocess system.

For ease of reference in the ensuing discussion, a generalizeddescription is set out below of FIG. 1, showing a schematicrepresentation of a thin film fabrication facility 10 including aneffluent abatement system 12 according to one embodiment of the presentinvention.

In the FIG. 1 facility, an organometallic source reagent or precursormaterial is furnished from source 14 thereof. The source 14 may comprisea reservoir containing a solution of the precursor material, or theprecursor in neat form, if it is in a liquid state at the supplyconditions. Alternatively, the source 14 may comprise a blending orsynthesis unit wherein the precursor is made or formulated in the firstinstance.

From the source 14, the liquid precursor flows in line 16 to thevaporizer unit 18, wherein the liquid precursor is flash vaporized forvolatilization thereof to form corresponding precursor vapor.Concurrently, if desired, a carrier gas, such as argon, helium,hydrogen, etc., is flowed from the carrier gas source 20 in line 22 tothe vaporizer unit 18. The carrier gas thus entrains the precursor vaporand forms a precursor vapor mixture.

The precursor vapor mixture flows in line 24 from the vaporizer unit 18to the CVD reactor 26, being dispersed in the interior volume of thereactor by showerhead discharge device 28 as a vapor flow stream 30.This stream of precursor vapor mixture thereby is directed to andimpinges on a wafer substrate 32 positioned on susceptor 34 heated byheating element 36. The wafer substrate is maintained at a sufficientlyelevated temperature to cause decomposition of the precursor vapormixture and chemical vapor deposition of the desired component of theprecursor on the surface of the wafer substrate.

An effluent comprising waste gases and decomposition by-products isdischarged from the reactor 26 and flows in line 38 to the effluentabatement system 12.

The effluent abatement system 12 optionally comprises a pre-pump heatingdevice 40 that may comprise any suitable means for heating the effluentto appropriate temperature. Such means may for example comprise a heatexchanger through which the effluent is flowed, a heat-tracing on theline 38, an embedded resistance heating element disposed in the line forheating of the effluent gas stream as it flows therethrough, a packedcolumn of high heat capacity packing elements that are continuously orintermittently heated, e.g., by infrared heating means, a heat pipeunit, or any other means by which the effluent is suitably heated toappropriate temperature.

From the optional pre-pump heating device 40, the effluent flows in line42 to the pump 44, which serves as a motive fluid driver for theeffluent stream. While a pump is illustratively shown, it will beappreciated that any other motive fluid driver may be employed, e.g., acompressor, eductor, turbine, fan, blower, etc. The pump may beconstructed and operated to provide an appropriate pressure level in theupstream reactor 26, e.g., a subatmospheric pressure level.

The pump 44 discharges the effluent into discharge line 46, from whichit flows to the optional post-pump cold trap 48. In the cold trap 48,condensable and/or solidifiable components may be extracted from theeffluent under appropriate temperature conditions, and discharged fromthe cold trap in line 50 for recovery and/or reuse. The treated effluentis flowed from the cold trap 48 in line 52 to the sorbent bed 54.

The sorbent bed 54 suitably comprises a vessel containing a sorbentmaterial having sorptive affinity for the components of the effluentthat are to be removed. Sorbent materials may include physicaladsorbent(s) and/or chemisorbent(s), as desired and appropriate to theremoval operation to be carried out.

Although illustratively shown as comprising a single adsorber unit, thesorbent bed may in fact be a multiple bed arrangement comprising sorbentbeds variously connected in series and/or parallel (manifolded)arrangements.

After sorptive treatment in the sorbent bed 54, the resultantly treatedeffluent is flowed from the sorbent bed in line 58, and may bedischarged to the atmosphere or further treated or processed, asnecessary or desired in a given end use application of the invention.

For regeneration purposes, the vessel containing the sorbent bed may bewrapped with a heating coil 56. The heating coil may comprise anelectrical resistance heating tape, a stream-tracing line, a heatexchange coil through which a suitable heat transfer fluid may beselectively flowed, or any other appropriate heating means.Alternatively, the vessel may be jacketed, to permit flow of a heatexchange fluid through the jacket for heating the sorbent materialcontained in the vessel.

As an additional feature accommodating regeneration of the sorbent bed,the sorbent bed may be coupled with a source 68 of a regeneration fluid,which is selectively flowable in line 70 to the heater 72 for heating toelevated temperature appropriate to effect desorption of the sorbedspecies from the sorbent bed during the regeneration operation.

The resultantly heated fluid is flowed from the heater 72 in line 74 tothe sorbent bed, and flows therethrough to effect desorption.

It will be appreciated that the heater 72 is optional and that in someinstances the desired desorption of the sorbed species from the sorbentbed may be effected solely by mass transfer as a result of aconcentration differential between the sorbent and the regeneration gasflowing through the sorbent bed.

The sorbent bed is also equipped with a discharge line 76 for efflux ofthe regeneration gas subsequent to its contacting with the sorbent inthe sorbent bed. The line 76 may be coupled with a recovery unit 78, inwhich separation of the desorbate gas may be effected, to recovercomponents thereof for final disposition, recycle or other use. In theillustrated recovery unit, the desorbate gas is separated into a firstfraction, which is discharged from the recovery unit in line 80, and asecond fraction, which is discharged from the recovery unit in line 82.

Any other suitable means and modes of regeneration of the sorbent bedmay usefully be employed.

At the outlet end of the sorbent bed 54 is provided an effluent tap line60, which conveys a side-stream of the effluent gas to an endpointdetector 62, as hereinafter more fully described.

The endpoint detector 62, upon detecting the breakthrough or incipientbreakthrough of one or more species in the effluent being monitored,generates a control signal that is transmitted in transmission line 64to the central processing unit (CPU) 66, which may be operativelyarranged to effect a corresponding action in the facility.

For example, the system may be arranged so that on incipientbreakthrough detection by the endpoint detector, the effluent flow isdiverted to a second sorbent bed, or to a holding (surge) vessel forretention until the regeneration of the sorbent bed has been carriedout.

Alternatively, or additionally, such endpoint breakthrough detection maybe employed to initiate a regeneration sequence, to renew the exhaustedsorbent bed for subsequent on-stream operation.

The features and layout of the semiconductor manufacturing facilityshown in FIG. 1 are illustrative in character only, and any othersuitable features, arrangements and operation may be advantageouslyemployed.

An embodiment of the invention for abatement of effluent from anillustrative CupraSelec™ process will now be described.

In such embodiment, a bed of chemisorbent or physisorbent material isemployed after the pump, to remove any residual Cu(hfac)TMVS, Cu(hfac)₂,and TMVS in the effluent deriving from the upstream CupraSelec™ process.This sorbent material may also be utilized to capture H(hfac), H(hfac)dihydride and metallic copper passing through the system. Smallinnocuous organic fragments from the upstream CVD process chamber may beadsorbed by the sorbent bed or the sorbent bed may be constructed sothat such fragments pass through the bed. The bed may be of any suitabletype, e.g., a fixed bed, a trickle bed, a fluidized bed, a recirculatingfluidized bed, etc.

The sorbent bed optionally may be used in conjunction with a pre-pumpheating device (pre-pump here being used to denote an upstream positionpreceding the pump in the line discharging effluent from the chemicalvapor deposition reactor), to convert the Cu(hfac) TMVS to Cu(hfac)₂ andan adduct moiety. Alternatively, no pre-pump heating device may benecessary.

The sorbent bed additionally or alternatively may be optionally used inconjunction with a post-pump cold trap for removing Cu(hfac)₂. In someinstances, no post-pump cold trap is necessary.

The abatement system of the invention may therefore variously comprise:a) a sorbent bed, b) a pre-pump heated tube, a pump, and the sorbentbed, c) a pre-pump heated tube, a pump, a post-pump cold trap, and thesorbent bed, or d) any other configuration utilizing suitable componentsselected from, or at a minimum including, one or more of these listeditems.

In an illustrative configuration, the sorbent bed comprises a bed ofsuitable sorbent material, e.g., high surface area activated carbon.Such sorbent material will remove heavy organometallic species, as wellas the precursor adduct molecule. Activated carbon may be used in any ofa number of grades, including high purity bead activated carbon, coconutcarbon, bituminous carbon, etc. The sorbent may alternatively comprisecarbon impregnated with permanganate, or Wetlerite™ carbon with somemetal oxide content providing oxidative properties to the sorbentmaterial.

In addition, special catalytic carbons can be used, such as thosecommercially available from Calgon Carbon Corporation as part of theirCentaur product line. These carbons are formulated to have especiallyhigh catalytic properties, but without the addition of metal oxides.Illustrative Centaur carbons include those described in U.S. Pat. No.5,356,849 and U.S. Pat. No. 5,494,869, the disclosures of which arehereby incorporated herein by reference in their entireties.

In addition to, or instead of, activated carbon, a high surface areaalumina can be used to physically adsorb the Cu(hfac)₂ and Cu(hfac)TMVS,as well as to physically trap the Cu(hfac)₂ and any H(hfac). A “wet”alumina may be employed if desired. A high surface area alumina may beimpregnated with a strong oxidizer, such as KMnO₄, to partially oxidizethe TMVS. CuSO₄-impregnated silica gel may also be employed to provide alesser oxidizing action, as desired.

In this respect, some oxidizer species that are effective for speciessuch as SiH₄, due to the favored tendency of oxygen from the oxidizeragent to bond with Si, are not sufficiently strong to oxidize TMVS,since in TMVS the silicon atom is surrounded or buffered by carbonatoms.

KMnO₄ is of sufficient strength to oxidize the TMVS to alcohols, e.g.,trimethyl silanol ((CH₃)₃SiOH), ethanol (CH₃CH₃OH) and (CH₃)₃SiCH₂CH₂OH.An alumina bed will have some affinity for these alcohols;alternatively, a carbon bed after the alumina bed may be employed sothat partially oxidized TMVS fragments are adsorbed on the alumina orthe activated carbon, while innocuous fragments pass through the system.

In addition to, or instead of activated carbon and/or high surface areaalumina, Cu₂O can be employed to both physically remove and partiallyreact the TMVS-related species.

Cu₂O can be utilized in the effluent abatement system to react theincoming species of H(hfac) and TMVS, to yield Cu(hfac)TMVS, which cansubsequently be abated with an activated carbon bed or a bed of alumina.The Cu₂O in this manner is irreversibly reacted according to thefollowing reactions:

Cu₂O+2 H(hfac)→Cu(hfac)₂+Cu(metal)+H₂O

Excess Cu₂O+H(hfac)+TMVS→Cu(hfac)TMVS+CuOH

Using excess Cu₂O reduces the first reaction. The above reactionseffectively trap the H(hfac) and, to a lesser degree, TMVS. Suchtrapping action may be particularly attractive in the event that apre-pump heated tube and/or cold trap is not used, since it allowsincoming gases to yield Cu(hfac)₂ and Cu(hfac)TMVS, which are readilyabated in the practice of the invention.

Another approach is to utilize a bed of alumina over a bed of Cu₂O. Thealumina in the overlying bed will physisorb the Cu(hfac)₂. The Cu₂O canthen be used to react with the process effluents to form Cu(hfac)TMVS.This approach is particularly advantageous when provision is made totrap the resultant Cu(hfac)TMVS at the end of the abatement treatment.

Still another approach is to utilize a bed of alumina (or aluminaimpregnated with a strong oxidizer) over a bed of carbon, as a componentof the abatement system.

The abatement system may further, optionally comprise an endpointdetection device, as a means of detecting endpoint or depletion of thesorbent material. The endpoint detection device may for examplecomprise:

a) a piezoelectric quartz crystal microbalance, with the quartz crystalcoated with a thin film coating having affinity for a component of thegas;

b) a colorimetric material, such as KMnO₄-impregnated alumina, which canbe located in a sightglass (protected from normal light in order toprevent colorimetric property degradation), and which will change colorupon oxidation;

c) a thermal conductivity detector on the exhaust of the system; and/or

d) an infrared (IR) device, such as a non-dispersive infrared (NDIR)system.

Any of various other endpoint detection schemes could alternatively beused.

The abatement device can also be combined with a method and apparatusfor recycle of the hfac material, if a reversible physisorptive materialis employed as the sorbent medium. Upon depletion, the spent canister ofphysisorbent/chemisorbent material can be removed from the effluentabatement system and can be returned to a regeneration site. At thissite heat, vacuum, or both, can be applied to the bed, therebyrevolatilizing some or all of the physically adsorbed material. Incertain cases when carbon is used as a physisorbent material, it may beadvantageous to pyrolyze the carbon, to volatilize the sorbed speciesand effect their release from the sorbent.

Due to the differing physisorption characteristics of organic andorgano-metallic species, the various adsorbed species will elute atdifferent times in the regeneration heat-up or vacuum cycle.

This chromatographic characteristic of the process can be used toseparate the valuable sorbate components of the effluent gas from thenon-valuable sorbate components. The valuable sorbate components canthen be recycled back to the precursor manufacturing process, while thenon-valuable components can be disposed of by other means, such asincineration.

Alternatively, the non-valuable sorbate components can be left on theadsorbent media and the adsorbent media can be either incinerated orlandfilled. In yet another alternative approach, the regeneratedphysisorbent/chemisorbent material can be recycled and reused in the CuCVD effluent abatement process itself.

The present invention also contemplates an apparatus for theregeneration of the spent physisorbent/chemisorbent material. Thisdevice comprises a heating element, preferably of a conductive contactor a radiative infrared type, e.g., wrapped around the canister to beregenerated. This first heater prevents heat losses from the bed andeliminates cold spots along the walls, as well as forcing heat into thebed itself.

The first heater will typically rely on conductive mechanisms totransfer heat within the bed itself. In this respect, the thermalconductivity of porous beds is typically poor due to the point- and/orsmall area-contacts that provide the conductive path for heat transfer.For large diameter beds, this discontinuity of the heat conduction path(due to void volume and interstitial spaces) may be insufficient toallow acceptably short heat-up times for the bed to be achieved, andother heating means and method must be alternatively employed.

Accordingly, where large diameter beds are employed, it may be desirableto use a second convective heater assembly whereby a carrier gas (suchas N₂, Ar, air, etc.) is passed through a heating device to raise thegas temperature, and the resultantly heated gas is then passed throughthe physisorbent/chemisorbent bed to be regenerated. In this manner,heat from the carrier gas is applied to the bed.

This second convective heater may be filled with heat transferenhancement media, such as turbulators, spheres, packing media such asPall® rings or Intalox® saddles, twisted tape inserts, delta winginserts, or spiral wound wire inserts (such as those manufactured by CalGavin).

The second convective heater may utilize a direct, electrically heatedelement, or it may use indirect heating (such as inductive heating, etc)to heat the carrier gas. Combustion-based heating may also be used ifsuch mode of heating is compatible with the sorbent material;combustion-based heating should generally not be employed with activatedcarbon sorbents, due to the flammable nature of many activated carboncompositions.

A vacuum device with throttling means (such as a valve, or a variableflow device (VFD)) may also be provided for vacuum regeneration of thecanister. The exhaust of the canister or the vacuum pump may then be fedinto a recovery unit, e.g., a condenser, a feed line into a precursormanufacturing unit (whereby the recovered component is reused forsynthesis of the source reagent), a reaction vessel, or a distillationrecovery process unit.

As an illustrative embodiment of one endpoint detection system inaccordance with the present invention, a test was run using a quartzmicrobalance (QMB) sensor element coated with a simple polymeric coatinghaving affinity for the organic and organometallic components of theeffluent.

The polymeric coating is non-reactive with the targeted organic andorganometallic species, but has the property of establishing anequilibrium between the vapor phase organic/organometallic species andthe same species adsorbed on the polymeric coating. As a result of thisequilibrium, when little or no organic passes through the scrubbervessel, little or no organic is adsorbed onto the polymeric coating ofthe QMD sensor.

However, when organics start to pass through the scrubber, equilibriumconstraints cause some of the organic to be adsorbed onto the polymericcoating of the QMB. This resultantly effects a weight change of the QMBand a concomitant change in the frequency output of the QMB. Such changein frequency output may be used to trigger a signal of a suitable type(auditory, visual, tactile, etc.) indicating that the canister hasreached endpoint and requires change-out.

This endpoint detection scheme is very versatile in that any of a numberof coatings, including hydrophobic or hydrophilic coatings, can beapplied to the QMB in order to target specific organic or organometallicspecies of interest. The QMB sensor preferably utilizes reversiblechemistry, so that a slow bleed of organic through the system does notcause false “trips” of the system.

For detection of TMVS, the QMB (AT-cut quartz crystal) may be coatedwith Carbowax 20M (polyethylene glycol with molecular weight 20,000grams per mole) by spray coating a solution of 0.33 grams of Carbowax inabout 200 ml of MeOH/acetonitrile (20:75 v:v). The active loading of thepolymer is about 2 milligrams total which translates to about an 8000Hz. frequency shift on the crystal from the uncoated base frequency.

Such QMB technology also can be used in conjunction with variousselective adsorbents or traps, in order to allow only target species topass through to the sensor. For instance, if the QMB sensor coating maytend to physisorb H₂O molecules in circumstances where H₂O is present ormay be highly variable in concentration, then a water removal unit,e.g., a Permapure® filter, may be used to remove the bulk of the H₂Omolecules from the effluent being monitored by the QMB endpointdetector.

Alternatively, other low cost means of endpoint monitoring may beutilized in the broad practice of the present invention. For example,Kitigawa tubes may be used, having chemistries utilizing Cr(VI) orCr(VI) and H₂SO₄. Some of these tubes give color changes when themonitored component is present and others do not, but such tubes utilizechemistries that can be used as a simple endpoint monitoring means.

Specific endpoint monitoring means may for example comprise:

a) the use of sample tubes with Cr(VI) or Cr(VI)+H₂SO₄ characteristics,for periodic “spot sampling” of the exhaust stream of the CVD reactor,

b) the incorporation of a sight glass on the scrubber canister, withCr(VI) or Cr(VI)+H₂SO₄ chemistry impregnated onto the resin behind thesight glass, so as produce a visually discernible color change as theend portion of the scrubber resin (sorbent material) is contacted byorganic molecules of interest, or

c) the incorporation of Cr(VI) or Cr(VI)+H₂SO₄ chemistry in an automatedmonitor using a colorimetric sensing tape, such as that manufactured byZellweger Analytics and employed in their company's MDA line ofmonitoring systems.

Another example of a chemistry that is potentially usefully employed inthe broad practice of the invention comprises a high surface aluminaabsorbent loaded with KMnO₄ for colorimetric indication upon exposure toorganic molecules. A distinct color change is observable after reactionwith organic species. This strong oxidizing chemistry can be used inconjunction with any of the physical methods described hereinabove inorder to detect an endpoint condition.

For abatement of Cu(hfac)TMVS or Cu(hfac)-organic ligand species, a bedof high surface area organic adsorbent can be used, such as carbon, ororganic polymer adsorbents such as Dow Sorbathene® pellets or Rohm andHaas Amberlite® pellets. A bed of high surface inorganic material canalso be used, such as alumina, molecular sieve, silica gel, hydrophobiczeolites, hydrophilic zeolites, etc. In addition, a bed of high surfacearea adsorbent (either organic or inorganic) impregnated with a strongoxidizer, such as KMnO₄, could also be utilized for some or all of thesorbent bed.

Thus, while the invention has been described herein with reference tospecific features and illustrative embodiments, it will be recognizedthat the utility of the invention is not thus limited, but ratherextends to and encompasses other features, modifications and alternativeembodiments, as will readily suggest themselves to those of ordinaryskill in the art based on the disclosure and illustrative teachingsherein. The claims that follow are therefore to be construed andinterpreted, as including all such features, modifications andalternative embodiments within their spirit and scope.

What is claimed is:
 1. A method for abatement of effluent from a processfor depositing copper on a substrate from an organometallic coppersource reagent, said method comprising contacting the effluent with asorbent material having sorptive affinity for said copper source reagentand decomposition products thereof, to at least partially removeresidual copper source reagent and decomposition products from theeffluent, wherein said sorbent material is selected from the groupconsisting of inorganic sorbent and organic polymer sorbent.
 2. Themethod of claim 1, wherein the sorbent material comprises a physicalsorbent.
 3. The method of claim 1, wherein the sorbent materialcomprises a chemisorbent.
 4. The method of claim 1, wherein a pump isdisposed upstream of the sorbent material, and said pump is operative tomaintain predetermined pressure conditions in the copper depositionprocess.
 5. The method of claim 4, further comprising a pre-pump heatingdevice operative to convert source reagent in the effluent todecomposition species thereof.
 6. The method of claim 5, furthercomprising a post-pump cold trap operative to remove residualdecomposition products from the effluent.
 7. A method for abatement ofeffluent from a CVD process for depositing copper on a substrate from aCu(hfac)TMVS source reagent, said method comprising flowing the effluentfrom the CVD process through a sorbent bed having sorptive affinity forCu(hfac)TMVS, Cu(hfac)₂ and TMVS, to remove residual Cu(hfac)TMVS,Cu(hfac)₂ and TMVS from the effluent, wherein said sorbent bed comprisesa sorbent material selected from the group consisting of inorganicsorbent and organic polymer sorbent.
 8. The method of claim 7, whereinthe sorbent bed comprises a physical sorbent.
 9. The method of claim 7,wherein the sorbent bed comprises a chemisorbent.
 10. The method ofclaim 7, wherein the sorbent bed is effective to capture H(hfac),H(hfac) dihydride and metallic copper from the effluent flowedtherethrough.
 11. The method of claim 7, wherein the sorbent bed has abed conformation selected from the group consisting of fixed beds,trickle beds, fluidized beds, and recirculating fluidized beds.
 12. Themethod of claim 7, wherein a pump is disposed upstream of the sorbentbed, and is operative to maintain predetermined pressure conditions inthe CVD process.
 13. The method of claim 12, further comprising apre-pump heating device operative to convert Cu(hfac)adduct species inthe effluent to Cu(hfac)₂ and adduct moieties.
 14. The method of claim12, further comprising a post-pump cold trap operative to removeCu(hfac)₂ from the effluent.
 15. The method of claim 13, furthercomprising a post-pump cold trap operative to remove Cu(hfac)₂ from theeffluent.
 16. The method of claim 7, wherein the sorbent bed comprisesan activated carbon sorbent.
 17. The method of claim 16, wherein theactivated carbon sorbent includes a sorbent selected from the groupconsisting of bead activated carbon, coconut carbon, bituminous carbon,and mixtures thereof.
 18. The method of claim 7, wherein the sorbent bedcomprises a carbon sorbent.
 19. The method of claim 18, wherein thecarbon sorbent further comprises permanganate.
 20. The method of claim18, wherein the carbon sorbent further comprises a metal oxide.
 21. Themethod of claim 7, wherein the sorbent bed comprises a catalytic carbonsorbent.
 22. The method of claim 7, wherein the sorbent bed comprises aninorganic adsorbent material.
 23. The method of claim 7, wherein thesorbent bed comprises an inorganic material selected from the groupconsisting of: alumina, molecular sieves, silica gels, zeolites.
 24. Themethod of claim 7, wherein the sorbent bed comprises alumina impregnatedwith an oxidizer.
 25. The method of claim 24, wherein the oxidizercomprises potassium permanganate.
 26. The method of claim 7, wherein thesorbent bed comprises silica impregnated with copper sulfate.
 27. Themethod of claim 7, wherein the sorbent bed comprises an adsorbent massof activated carbon and an adsorbent mass of alumina.
 28. The method ofclaim 7, wherein the sorbent bed comprises Cu₂O.
 29. The method of claim7, wherein the sorbent bed comprises Cu₂O and an adsorbent mass ofactivated carbon.
 30. The method of claim 7, wherein the sorbent bedcomprises Cu₂O and an adsorbent mass of alumina.
 31. The method of claim7, wherein the sorbent bed comprises an adsorbent mass of activatedcarbon and an adsorbent mass of alumina impregnated with an oxidizer.32. The method of claim 7, further comprising monitoring the effluentdischarged from the sorbent bed, to detect breakthrough of a selectedcomponent.
 33. The method of claim 32, wherein the monitoring comprisesexposure of the effluent to a colorimetric medium exhibiting acolorimetric change upon breakthrough of said selected component. 34.The method of claim 32, wherein the monitoring comprises detecting thethermal conductivity of the effluent.
 35. The method of claim 32,wherein the monitoring comprises non-dispersive infrared monitoring. 36.The method of claim 32, wherein the monitoring comprises exposing theeffluent to a quartz microbalance detector comprising a piezoelectriccrystal having on a surface thereof a coating with affinity for theselected component of the effluent, whereby the piezoelectric crystalexhibits a change in frequency characteristics indicative ofbreakthrough of the selected component of the effluent.
 37. The methodof claim 36, wherein the coating exhibits reversible affinity for theselected component.
 38. The method of claim 36, wherein the coating isselected from the group consisting of hydrophilic coatings andhydrophobic coatings.
 39. The method of claim 32, further comprisingremoving water from the effluent before the effluent contacts thecoating of the piezoelectric crystal.
 40. The method of claim 32,wherein the monitoring comprises exposing the effluent to a chemistrycomprising Cr(VI) or Cr(VI) and H₂SO₄.
 41. The method of claim 32,wherein the monitoring comprises impregnating an outlet end portion ofthe sorbent bed with a colorimetric chemistry evidencing a visuallydiscernible colorimetric change upon breakthrough of the selectedcomponent of the effluent, and disposing a sight glass in viewingrelationship to the impregnated outlet end portion of the sorbent bed.42. The method of claim 7, wherein hfac material is sorbed on thesorbent bed, and sorbed hfac is subsequently desorbed from the sorbentbed and recycled for synthesis of Cu(hfac)TMVS.
 43. The method of claim7, wherein the sorbent bed is regenerated by heat.
 44. The method ofclaim 7, wherein the sorbent bed is regenerated by vacuum desorption ofpreviously sorbed species therefrom.
 45. The method of claim 7, whereinthe sorbent bed is regenerated by pyrolysis.
 46. The method of claim 7,wherein the sorbent bed is regenerated by desorbing previously sorbedspecies therefrom, wherein said desorbing is carried out under varieddesorption conditions including a first desorption condition fordesorbing a first desorbate component and a second desorption conditionfor desorbing a second desorbate component.
 47. The method of claim 7,wherein the sorbent bed is regenerated in a first regeneration stepinvolving conductive transfer of heat to the sorbent bed, and isregenerated in a second regeneration step involving convective heatingby a heated gas flowed through the sorbent bed.
 48. The method of claim7, further comprising throttling the flow of gas through the sorbent bedto control vacuum pressure on the sorbent bed.
 49. The method of claim7, wherein effluent from the sorbent bed is flowed to a recovery unitfor recovery of a selected component of the effluent.
 50. The method ofclaim 49, wherein the recovery unit comprises a unit selected from thegroup consisting of condenser units, distillation units, synthesis unitsand reaction units.
 51. The method of claim 7, wherein the sorbent bedcomprises a sorbent material selected from the group consisting ofcarbon, organic polymers, alumina, molecular sieve, silica gel,hydrophilic zeolites, hydrophobic zeolites, and combinations thereof.52. A method for abatement of effluent from a CVD process using a sourcereagent having a metal organic loosely bound to a organic ororganometallic molecule such that upon exposure to heat such bond isreadily cleavable, said method comprising flowing the effluent from theCVD process through a sorbent bed having sorptive affinity for saidsource reagent and decomposition products thereof, to at least partiallyremove residual source reagent and decomposition products from theeffluent wherein said sorbent bed comprises a sorbent material selectedfrom the group consisting of inorganic sorbent and organic polymersorbent.
 53. The method of claim 52, wherein a pump is disposed upstreamof the sorbent bed, and is operative to maintain predetermined pressureconditions in the CVD process.
 54. The method of claim 52, furthercomprising monitoring the effluent discharged from the sorbent bed, todetect breakthrough of a selected component.
 55. The method of claim 54,wherein the monitoring comprises exposing the effluent to a quartzmicrobalance detector comprising a piezoelectric crystal having on asurface thereof a coating with affinity for the selected component ofthe effluent, whereby the piezoelectric crystal exhibits a change infrequency characteristics indicative of breakthrough of the selectedcomponent of the effluent.
 56. The method of claim 55, wherein thecoating exhibits reversible affinity for the selected component.
 57. Themethod of claim 55, wherein the coating is selected from the groupconsisting of hydrophilic coatings and hydrophobic coatings.
 58. Themethod of claim 55, further comprising removing water from the effluentbefore the effluent contacts the coating of the piezoelectric crystal.59. The method of claim 54, wherein the monitoring comprisesimpregnating an outlet end portion of the sorbent bed with acolorimetric chemistry evidencing a visually discernible colorimetricchange upon breakthrough of the selected component of the effluent, anddisposing a sight glass in viewing relationship to the impregnatedoutlet end portion of the sorbent bed.